The .50-70 Government Cartridge was the first metal cased cartridge used in an American service rifle, the Springfield Model 1866. It featured a .50 caliber (12.7mm) bullet made of lead and weighing 450 grains (29g). The charge was made of 70 grains (4.5kg) of black powder, ignited by a centrefire large rifle primer. The case was also rimmed.

The case could contain a pressure of 22,500 PSI, therefore imparting a lot of energy onto the bullet, improving the muzzle velocity.

The .50-70 Government cartridge was designed following the unsatisfactory results of the .58in (14.7mm) Minie Ball, used in the Springfield Model 1865. The Minie Ball had been in use since its invention in 1847 and the release of the Minie Rifle. However, by the 1860s the Minie Ball was becoming inefficient, as the muzzle loading technique was replaced by breechloading rifles, which were more efficient when using a cartridge. The Minie Ball (which had three grooves to improve its stability and would deform to fit the barrel and engage with the rifling to spin) would not cope with being placed in a cartridge made of anything other than paper, which couldn't contain a lot of pressure and was susceptible to water. Therefore the need for a replacement emerged.

The .50-70 Government Cartridge fulfilled this role, using a metal jacket to protect the bullet and powder when not in use, allowing for easier and safer transport of the ammunition. The cartridge was issued as the "US Centre-fire Metallic Cartridge" before it was replaced by the .45-70 Government cartridge in 1873, with the release of the Springfield Model 1873.

The .50-70 Government cartridge left production following the change to the .45-70 Government cartridge in 1873, meaning that gunsmiths have had to manufacture their own ammunition to fit .50-70 caliber rifles. The most common version is a 430 grain (28g) bullet, launched by 70 grains (2.9g) of blackpowder.